Late transition metal catalyst complexes and oligomers therefrom

ABSTRACT

The invention is directed towards a composition comprising the formula LMX(X′) n  wherein n equals 0 or 1; X and X′ are independently selected from the group consisting of halides, hydride, triflate, acetates, borates, C 1  through C 12  alkyl, C 1  through C 12  alkoxy, C 3  through C 12  cycloalkyl, C 3  through C 12  cycloalkoxy, aryl, thiolates, carbon monoxide, cyanate, olefins, and any other moiety into which a monomer can insert; M is selected from the group consisting of nickel, palladium, and platinum and L is a nitrogen-containing bidentate ligand with more than two nitrogen atoms. The composition possesses a tetrahedral or pseudo-tetrahedral structure. The invention also provides a method for using the composition in conjunction with an activating cocatalyst to form short chain α-olefins.

FIELD OF THE INVENTION

The invention is directed towards a pseudotetrahedral late transitionmetal catalyst complex and its use in forming α-olefins.

BACKGROUND

The chemical industry uses α-olefins as intermediates in a variety ofprocesses. In particular, linear α-olefins are used in the formation ofpolyolefins such as ethylene butylene copolymers. Other products formedfrom α-olefins include surfactants, lubricants and plasticizers.Paraffin wax cracking, paraffin dehydrogenation and alcohol dehydrationprocesses can be used to produce α-olefins; however, most of the shortchain linear α-olefins currently used in the chemical industry areproduced by ethylene oligomerization. Ethylene oligomerization is adesirable route due to the availability and low cost of ethylene.Additionally, the product quality is also acceptable for mostapplications.

In recent years, the chemical industry has employed the use oforganometallic catalysts to produce polymers. While many advances inorganometallic catalyst technology have been made, researchers continueto seek superior catalyst compositions. In fact, very recently, novellate transition organometallic catalysts have been discovered which arevery effectively used in polymerization processes. More specifically,U.S. Pat. No. 6,037,297 to Stibrany et al., herein incorporated byreference, details group IB (Cu, Ag and Au) containing catalystcompositions that are useful in polymerization processes.

Organometallic catalyst technology is also a viable tool inoligomerization processes which produce linear α-olefins for use asfeedstock in various other processes. However, one problem oftenencountered when using many of these catalyst systems is the propensityto produce α-olefins with very low selectivity (i.e., a Schulz-Florytype distribution with high k values). For instance, many of the linearα-olefins made today utilize a neutral nickel (II) catalyst having aplanar geometry and containing bidentate monoanionic ligands. Whilethese planar nickel (II) catalysts do produce linear α-olefins, thesecatalysis systems exhibit a Schulz-Flory type of distribution over avery wide range (i.e., C₄-C₃₀₊).

To address Schulz-Flory distribution problem, chromium metal basedcatalysts have become popular for use in certain oligomerizationprocesses. More precisely, chromium complexes have been used tooligomerize ethylene in order to form linear α-olefins with improveddistributions. In fact, there has been a report of a specific chromiumcatalyst which selectively trimerizes ethylene to 1-hexene. Thesetechniques employ the use of a chromium compound in conjunction withaluminoxane along with one of a variety of compounds such as nitrites,amines and ethers. Unfortunately, while these techniques have been ableto selectively produce α-olefins, polymer is formed as a co-product. Ofcourse, when polymer is co-produced, the yield of desirable productdecreases accordingly. Also, as a practical matter, polymer build-up inthe reaction vessel can severely hamper production efficiency therebylimiting the commercial use of such processes.

As discussed above, the organometallic catalyst technology now beingused to produce α-olefins has two major disadvantages. First, many ofthe organometallic catalysts produce α-olefins with a Schulz-Flory typedistribution. Unfortunately this Schulz-Flory type distribution is notideal when short chain α-olefins are desired—in other words, theselectivity is not good enough to maintain efficient processes. Becauseα-olefins are used as inter-mediates for specific products, α-olefinswith certain chain lengths are desired. For instance, the following areexamples of α-olefin chain lengths that would be desirable as feeds forcertain product types: C₄ to C₈ for comonomer in ethylenepolymerization; C₁₀ for lube quality poly-α-olefins; and C₁₂ to C₂₀ forsurfactant products. Thus, considerable inefficiency and waste ispresent when significant amounts of α-olefins produced having chainlengths outside of the range required for production of a particularchemical. Second, while some of the current organometallic catalysts mayimprove selectivity, most also produce polymer co-product. This lowersthe yield of desired product and can also accumulate in the reactionvessel—both of which make commercial use less attractive andinefficient. Hence, there is still a need for improving the selectivelyand efficiency of linear α-olefin production.

SUMMARY

The instant invention provides a late transition metal catalystcomposition having a pseudotetrahedral geometric structure and its usein forming α-olefins. The instant invention can be used to selectivelyproduce short chain α-olefins without producing a significant percentageof polymer co-product. Thus, the two problems noted above with regard tocurrent oligomerization processes are overcome.

In one embodiment, the invention is a composition having the formulaLMX(X′)_(n) wherein n equals 0 or 1; X and X′ are independently selectedfrom the group consisting of halides, hydride, triflate, acetates,borates, C₁ through C₁₂ alkyl, C₁ through C₁₂ alkoxy, C₃ through C₁₂cycloalkyl, C₃ through C₁₂ cycloalkoxy, aryl, thiolates, carbonmonoxide, cyanate, olefins, and any other moiety into which a monomercan insert; M is selected from the group consisting of nickel,palladium, and platinum and L is a nitrogen-containing bidentate ligandwith more than two nitrogen atoms.

In another embodiment, the invention is a catalyst compositioncomprising the reaction product of a composition having the formulaLMX(X′)_(n), as described above, and an activating cocatalyst. Thisembodiment of the invention is particularly useful in oligomerizationchemistry.

Also provided for is a method for selectively and efficiently producingshort chain linear α-olefins. The method includes contacting olefinicmonomers under oligomerization conditions with a catalyst compositioncomprising a composition having the formula LMX(X′)_(n), as definedabove, and an activating cocatalyst.

These and other features, aspects and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims, and accompanying FIGURE.

BRIEF DESCRIPTION OF DRAWING

The FIGURE shows one embodiment of the pseudotetrahedral crystalstructure of 2,2′-bis[2-(1-ethylbenzimidazol-2yl)]biphenyl]nickel(II)dichloride (hereinafter a.k.a., Ni(diEtBBIL)Cl₂).

DETAILED DESCRIPTION

The invention relates to a novel pseudotetrahedral metal complex which,when used with an activating cocatalyst, provides a novel catalystcomposition. The invention also provides a novel oligomerization methodwhich utilizes the catalyst composition. Generally speaking, the methodof the invention selectively produces oligomers. The term “oligomers” asused in this specification should be appreciated by one skilled in theart as meaning a α-olefin having approximately three to forty carbonatoms. More preferred “short chain” linear α-olefins have approximatelythree to twelve carbon atoms. Most preferred short chain linearα-olefins have approximately four to ten carbon atoms. Further, theolefinic monomers used to produce the linear α-olefins are defined asshort chain linear olefins such as ethylene, propylene and butene.Longer chain olefinic monomers such as hexene and octene may also beemployed to produce the linear α-olefins. It should also be appreciatedby those skilled in the art that although the term “pseudotetrahedral”is used to describe the geometric structure of the metal complex, itdoes not exclude a pure “tetrahedral” geometrical arrangement. Theprefix “pseudo” is used throughout the specification to most accuratelydescribe the non-limiting embodiments described herein.

More specifically, the invention is based upon the reaction of a groupVIIIA metal complex having a bidentate nitrogen ligand with apseudotetrahedral arrangement around the metal (e.g., Ni, Pd or Pt),with and activating cocatalyst such as methyl alumoxane (a.k.a., “MAO”).Furthermore, by controlling the temperature, catalyst loading, ligandstructure, and residence time, product selectivity can be adjusted toproduce individual α-olefins such as 1-butene with high selectivity(e.g., greater than 95%) or mixtures of linear or branched α-olefins ina narrow molecular weight range (e.g., C₄ to C₈ olefins).

The composition of this invention is a late transition metal complexhaving the formula LMX(X′)_(n) wherein n equals 0 or 1. X and X′ areindependently selected from the group consisting of halides, hydride,triflate, acetates, borates, C₁ through C₁₂ alkyl, C₁ through C₁₂alkoxy, C₃ through C₁₂ cycloalkyl, C₃ through C₁₂ cycloalkoxy, aryl,thiolates, carbon monoxide, cyanate, olefins including diolefins andcycloolefins, and any other moiety into which a monomer can insert. M isselected from the group consisting of nickel, palladium, and platinum. Lis a nitrogen-containing bidentate ligand having more than two nitrogenatoms.

In a preferred embodiment, X and X′ are independently selected from thegroup consisting chloride and bromide. In more preferred embodiment, Xequals X′.

In another preferred embodiment L has the formula A(ZR*)_(m)A′ or AA′wherein A and A′ are independently selected from the group consistingof:

wherein R1 is independently selected from the group consisting ofhydrogen, C₁ through C₁₂ alkyl, C₃ through C₁₂ cycloalkyl, aryl, andtrifluoroethyl; R2 and R3 are independently selected from the groupconsisting of hydrogen, C₁ through C₁₂ alkyl, C₃ through C₁₂ cycloalkyl,C₁ through C₁₂ alkoxy, F, Cl, SO₃, C₁ through C₁₂ perfluoroalkyl,trimethylsilyl, and N(CH₃)₂. Z is carbon and R* is independentlyselected from the group consisting of hydrogen, C₁ through C₁₂ alkyl, C₃through C₁₂ cyclo alkyl, aryl, C₁ through C₁₂ alkoxy, F, Cl, SO₃, C₁through C₁₂ perfluoroalkyl, trimethylsilyl, and N(CH₃)₂. Finally, mequals an integer from 1 to 22. In a preferred embodiment, m equals 1 or12.

Among the metal complexes of the present invention, those having thefollowing ligands are particularly preferred:1,1′-bis(1-methylbenzimidazol-2-yl)-1″-methoxymethane;1,1′-bis(1-butylbenzimidazol-2yl)pentane; and2,2′-bis(2-(1-ethylbenzimidazol-2-yl))biphenyl.

The 1,1′-bis(1-methylbenzimidazol-2-yl)-1″-methoxymethane ligand has thefollowing structure:

The 1,1′-bis(1-butylbenzimidazol-2yl)pentane ligand has the followingstructure:

The 2,2′-bis(2-(1-ethylbenzimidazol-2-yl))biphenyl ligand has thefollowing structure:

In another preferred embodiment, X and X′ are independently selectedfrom the group consisting of chloride and bromide. In a more preferredembodiment, X equals X′.

The invention also provides for the composition which is the reactionproduct of the composition having the formula LMX(X′)_(n), as definedabove, and an activating cocatalyst. In one embodiment, the activatingcocatalyst is selected from the group consisting of alkylalumoxanes,aluminum alkyls, aluminum halides, alkyl aluminum halides, Lewis acids,alkylating agents, and mixtures thereof. In a more preferred embodiment,the activating cocatalyst is methyl alumoxane. Finally, the preferredratio of metal complex to activating cocatalyst is from 1:10⁻² to 1:10⁶.

Lewis acids other than any of the foregoing list and the mixtures of theforegoing can also be used in conjunction with alkylating agents, suchas methyl magnesium chloride and methyl lithium. Examples of such Lewisacids are those compounds corresponding to the formula: R″″₃B, where R″″independently each occurrence is selected from hydrogen, silyl,hydrocarbyl, halohydrocarbyl, alkoxide, aryloxide, amide or combinationthereof, said R″″ having up to 30 nonhydrogen atoms.

It is to be appreciated by those skilled in the art, that the aboveformula for the preferred Lewis acids represents an empirical formula,and that many Lewis acids exist as dimers or higher oligomers insolution or in the solid state. Other Lewis acids which are useful inthe catalyst compositions of this invention will be apparent to thoseskilled in the art.

Other examples of suitable cocatalysts are discussed in U.S. patentapplication Ser. No. 09/212,035 filed Dec. 15, 1998 by Stibrany et al.;U.S. Pat. No. 5,198,401 and PCT patent documents PCT/US97/10418 andPCT/US96/09764, all incorporated by reference herein.

The composition described above may also be supported. The supportmaterial is preferably a porous material which includes, but is notlimited to, inorganic oxides, talc, and inorganic chlorides. The supportmaterial may also be resinous materials such as polystyrene polyolefinor polymeric compounds. The support material may also be any otherorganic material that has an average particle size greater thanapproximately 10 micron. These catalysts are generally physisorbed onthe support. The catalysts can also be supported on mesoporousmaterials. In a more preferred embodiment, the composition is supportedby silica.

The novel composition of the invention can be used in conjunction with acocatalyst to oligomerize olefinic monomers. Thus, the invention alsoprovides a method for producing linear α-olefins by contacting olefinicmonomers with the composition described above under certain temperatureand pressure conditions conducive to forming oligomers while minimizing,or totally eliminating, any polymer co-product. Olefinic monomers usedfor producing the linear α-olefins include, but are not limited to,ethylene, propylene, butenes, and mixtures thereof. A preferred olefinicmonomer is ethylene. In one embodiment, the invention produces linearα-olefins having approximately four to twenty carbon atoms. In a morepreferred embodiment, the invention produces α-olefins having four toeight carbon atoms.

Generally, oligomerization may be accomplished utilizing similartemperatures and pressures used in the prior art. More specifically,temperature ranges from about −100 to 250° C. and at pressures fromabout 5 to 30000 psig are acceptable. The most preferred temperaturerange is from about 0° C. to 100° C. while the preferred is about 15 to2000 psig.

Furthermore, oligomerization may take place in a solvent, neat (e.g., nosolvent and liquid condensed olefin), or in a gas phase (e.g., olefin ingas phase and catalyst in the solid phase). When oligomerization isconducted in a solvent phase, suitable solvents include, but are notlimited to, ethylene, propane, butane, pentane, hexane, toluene,methylene chloride, carbon dioxide and mixtures thereof.

As for oligomerization in a gas phase, Exxon Chemical's gas phasecatalyst technology as described in U.S. Pat. No. 5,554,704 which isherein incorporated by reference. U.S. Pat. No. 5,554,704 teaches aprocess for producing a supported catalyst. The supported catalyst canthen be used in a solvent free system wherein gas phase α-olefin ispassed through a fixed bed of catalyst. The condensed α-olefin productis then separated from the system.

The bidentate ligands of the invention can be synthesized usingtechniques well known to those skilled in the art. See U.S. Pat. No.6,037,297 to Stibrany et al., herein incorporated by reference, whichexplains how to synthesize bidentate ligands and also shows thestructure of such ligands. The novel pseudotetrahedral metal complex canbe synthesized by complexing a nickel, palladium or platinum compoundwith the ligands. This is most easily done by dissolving the nickel,palladium or platinum compound in a solvent then adding ligand andsolvent. This mixture is then refluxed and cooled.

The invention is further described in the following non-limitingexamples.

EXAMPLES

I. Catalyst Preparation

Example 1

Preparation of [1,1′-bis(1-methylbenzimidazol-2yl)1″methoxymethane]nickel(II) dibromide (a.k.a., “Ni(HBBIOMe)Br₂”)

A 100 mg (0.45 mmol) quantity of NiBr₂ was dissolved in 20 mL of ethanolto give a yellow solution. After the addition of 146 mg (0.46 mmol) of1,1′bis(1 -methylbenzimidazol-2yl)1″methoxymethane (prepared usingtartronic acid 1,2 phenylenediamine with iodomethane as the alkylatingagent as described in U.S. Pat. No. 6,037,297 to Stibrany et al., hereinincorporated by reference) and the addition of 10 mL of toluene, themixture was refluxed and stirred for 10 minutes. Upon cooling themixture gave a pale-violet crystalline precipitate with a pale-greensupernatant. The crystalline solid was collected by filtration andwashed with about 10 ml of hexane. Upon drying in air 201 mg ofpale-violet crystalline product was obtained (81.7% yield).

Example 2

Preparation of [1,1′bis(1-butylbenzimidazol-2yl)pentane]nickel(II)dichloride (a.k.a., “Ni(tributBBIM)Cl₂”)

A 100 mg (0.42 mmol) quantity of NiCl₂·6H₂O was dissolved in 20 mL ofabsolute ethanol to give a yellow-green solution. Then 190 mg (0.46mmol) of tributBBIM was added followed by the addition of 1 mL oftriethylorthoformate. The solution was heated to gentle reflux for ca. 5min. Upon cooling violet dichroic blades formed and 227 mg of solid wascollected by filtration and washed with triethylformate followed bypentane. (98%), C₂₇H₃₆Cl₂N₄Ni, FW=546.22; mp 324-325° C. (decomp.);X-ray crystallographic data: monoclinic, a=14.0690 Å, b=14.1050 Å,c=14.3130 Å, α=90°, β=97.220°, γ=90°, V=2817.80 Å³.

Example 3

Preparation of ±2,2′-bis[2-(1-ethylbenzimidazol-2yl]biphenyl]nickel(II)dichloride (a.k.a., “Ni(diEtBBIL)Cl₂”)

A 100 mg (0.42 mmol) quantity of NiCl₂·6H₂O was dissolved in a mixtureconsisting of 15 mL of ethanol and 1.5 mL of triethylorthoformate togive a yellow-green solution. After the addition of 60 mg (0.14 mmol) of2,2′-bis[2-(1-ethylbenzimidazol-2yl)]biphenyl the mixture was warmed.Upon cooling, a bright-blue crystalline solid precipitated. Theprecipitate was collected by filtration and was then redissolved in 5 mLof warm nitromethane. The solution was filtered and upon standingyielded bright-blue x-ray quality prisms. The following crystallographicdata and FIGURE illustrates the crystal structure of Ni(diEtBBIL)Cl₂.

The x-ray crystallographic data for the composition is as follows:

FW=572.16 g/mol

Space group=P2₁2₁2₁

a=9.854(1) Å

b=16.695(2) Å

c=16.844(2) Å

V=2771.0(5) Å³

Z=4

R=0.0469, wR²=0.0510

[Note: Bond lengths are in Angstroms while bond angles are in degrees.]

Ni(1)—N(3) 1.998(8) N(3)—Ni(1)—N(1) 111.1(3) N(3)—Ni(1)—Cl(1) 111.5(2)Ni(1)—Cl(1) 2.226(2) N(1)—Ni(1)—Cl(1) 101.1(2) N(3)—Ni(1)—Cl(2) 102.1(2)Ni(1)—N(1) 2.008(7) N(1)—Ni(1)—Cl(2) 107.6(2) Cl(1)—Ni(1)—Cl(2)123.41(11) Ni(1)—Cl(2) 2.233(3)

Example 4

Preparation of [1,1′bis(1-methylbenzimidazol-2yl)1=methoxymethane]nickel(II) dibromide (a.k.a., Ńi(HBBIOMe)Bŕ₂)

A 72 mg (0.36 mmol) quantity of NiBr₂ was added to a 20 mL solution of 1to 1 acetone:methanol containing 200 mg (0.65 mmol) of[1,1′bis(1-methylbenzimidazol-2yl) 1″ methoxymethane]_(HBBIMOMe) to givea pale violet solution upon mixing. After standing overnight,pale-violet crystals formed. These were collected by filtration and weredried under high vacuum. C₁₈H₁₈Br₂N₄NiO, FW=524.87.

II. Oligomerization

Example 5

Ethylene Oligomerization Using Ni(tributylBBIM)Cl₂

In an argon glovebox a toluene slurry was prepared in a 50 ml Parr glassliner by suspending Ni(tributBBIM)Cl₂ (FW 546.22) (8.3 mg, 1.52×10⁻²mmoles) (product of Example 2) in 7.95 g toluene followed by activationwith 2.04 mL of 30% MAO (Al/Ni=695) to obtain a dark suspension. In theglovebox, the glass liner was placed into the Parr reactor. The reactorwas transferred to a hood and then pressurized with 500 psig ofethylene. The solution was stirred (stirring rate 500 RPM) at 25° C. for12 minutes. During the reaction the pressure dropped to almost zeropsig. The reaction mixture was cooled and unreacted ethylene was ventedto obtain 2.8 g of product. The product was analyzed by gaschromatography-mass spectrometry. GC analysis of the product indicatedpeaks due to butenes (88%) and hexenes (12%). No peaks corresponding tohigher olefins were observed. Catalyst productivity was about 32900moles ethylene reacted/moles of Ni catalyst per hour.

Example 6

Ethylene Oligomerization Using Catalyst Ni(tributylBBIM)Cl₂

In an argon glovebox a toluene slurry was prepared in a 50 ml Parr glassliner by suspending Ni(tributBBIM)Cl₂ (FW 546.22) (8.3 mg, 1.52×10⁻²mmoles) (product of Example 2) in 8.17 g toluene followed by activationwith 2.05 mL of 30% MAO (Al/Ni=698) to obtain a dark suspension. In theglovebox, the glass liner was placed into the Parr reactor. The reactorwas transferred to a hood and then pressurized with 500 psig ofethylene. The solution was stirred (stirring rate 500 RPM) at 25° C. for30 minutes. During the reaction, the pressure dropped to almost zeropsig. The reaction mixture was cooled and unreacted ethylene was ventedto obtain 2.0 g of product. The product was analyzed by gaschromatography-mass spectrometry. GC analysis of the product indicatedpeaks due to butenes (89%) and hexenes (11%). No peaks corresponding tohigher olefins were observed. Catalyst productivity was about 9400 molesethylene reacted/moles of Ni catalyst per hour.

Example 7

Ethylene Oligomerization Using Catalyst Ni(diEtBBIL)Cl₂

In an Argon glovebox a toluene slurry was prepared in a 50 ml Parr glassliner by suspending Ni(diEtBBIL)Cl₂ (FW 572.16) (8.7 mg, 1.52×10⁻²mmoles) (product of Example 3) in 8.00 g toluene followed by activationwith 2.00 mL of 30% MAO (Al/Ni=681) to obtain a dark suspension. In theglovebox, the glass liner was placed into the Parr reactor. The reactorwas transferred to a hood and then pressurized with 500 psig ofethylene. The solution was stirred (stirring rate 500 RPM) at 25° C. for10 minutes, then the solution was heated to 80° C. and stirred for totalof 70 minutes. During the reaction, the pressure dropped to less than 50psig. The reaction mixture was cooled and unreacted ethylene was ventedto obtain 1.9 g of product. The product was analyzed by gaschromatography-mass spectrometry. GC analysis of the product indicatedpeaks due to butenes (92%) and hexenes (8%). No peaks corresponding tohigher olefins were observed. Catalyst productivity was about 3825 molesethylene reacted/moles of Ni catalyst per hour.

Example 8

Ethylene Oligomerization Using Catalyst Ni(diEtBBIL)Cl₂

In an argon glovebox a toluene slurry was prepared in a 50 ml Parr glassliner by suspending Ni(diEtBBIL)Cl₂ (FW 572.16) (8.3 mg, 1.45×10⁻²mmoles) (product of Example 3) in 8.00 g toluene followed by activationwith 2.00 mL of 30% MAO (Al/Ni=713) to obtain a dark suspension. In theglovebox, the glass liner was placed into the Parr reactor. The reactorwas transferred to a hood and then pressurized with 500 psig ofethylene. The solution was stirred (stirring rate 500 RPM) at 25° C. for30 minutes. During the reaction, the pressure dropped to less than 50psig. The reaction mixture was cooled and unreacted ethylene was ventedto obtain 1.8 g of product. The product was analyzed by gaschromatography-mass spectrometry. GC analysis of the product indicatedpeaks due to butenes (95%) and hexenes (5%). No peaks corresponding tohigher olefins were observed. Catalyst productivity was about 8860 molesethylene reacted/moles of Ni catalyst per hour.

Example 9

Ethylene Oligomerization Using Catalyst Ni(HBBIOMe)Br₂

In an argon glovebox a toluene slurry was prepared in a 50 ml Parr glassliner by suspending Ni(HBBIOMe)Br₂ (FW 524.87) (8.5 mg, 1.52×10⁻²mmoles) (product of Example 4) in 8.00 g toluene followed by activationwith 2.00 mL of 30% MAO (Al/Ni=680) to obtain a dark suspension. In theglovebox, the glass liner was placed into the Parr reactor. The reactorwas transferred to a hood and then pressurized with 500 psig ofethylene. The solution was stirred (stirring rate 500 RPM) at 25° C. for27 minutes. During the reaction, the pressure dropped to almost zeropsig. The reaction mixture was cooled and unreacted ethylene was ventedto obtain 2.3 g of product. The product was analyzed by gaschromatography-mass spectrometry. GC analysis of the product indicatedpeaks due to butenes (85%) and hexenes (15%). No peaks corresponding tohigher olefins were observed. Catalyst productivity was about 11980moles ethylene reacted/moles of Ni catalyst per hour.

Example 10

Gas Phase Ethylene Oligomerization Using Catalyst Ni(tributylBBIM)Cl₂

In an argon glovebox a toluene slurry was prepared in a 50 ml Parr glassliner by suspending Ni(tributBBIM)Cl₂ (FW 546.22) (8.3 mg, 1.52×10⁻²mmoles) (product of Example 2) in 8.01 g toluene followed by activationwith 2.02 mL of 30% MAO (Al/Ni=688) to obtain a dark suspension. Thesolvent was removed under high vacuum and the residue or powder wasloaded into 50 ml Parr reactor under nitrogen. The Parr reactor waspressurized with 350 psig of ethylene at 25° C. Within 3 hours, theethylene pressure dropped from 350 psig to 80 psig. The reaction mixturewas cooled and unreacted ethylene was vented to obtain 1.8 g of product.The product was analyzed by gas chromatography-mass spectrometry. GCanalysis of the product indicated peaks due to butenes (70%) and hexenes(30%). No peaks corresponding to higher olefins were observed.

Example 11

Gas Phase Ethylene Oligomerization Using Catalyst Ni(tributylBBIM)Cl₂

In an argon glovebox a toluene slurry was prepared in a 50 ml Parr glassliner by suspending Ni(tributBBIM)Cl₂ (FW 546.22) (8.9 mg, 1.63×10⁻²mmoles) (product of Example 2) in 8.04 g toluene followed by activationwith 2.01 mL of 30% MAO (Al/Ni=638) to obtain a dark suspension. Thesolvent was removed under high vacuum and powder was placed into a glassflitted vessel. The fritted vessel was placed into a 50 ml Parr glassliner, thus suspending the powdered catalyst. The Parr reactor waspressurized with 350 psig of ethylene at 25° C. Within 3 hours, theethylene pressure dropped from 350 psig to 80 psig. The reaction mixturewas cooled and unreacted ethylene was vented to obtain 1.26 g ofproduct. The product was analyzed by gas chromatography-massspectrometry. GC analysis of the product indicated peaks due to butenes(82.4%) and hexenes (17.6%). No peaks corresponding to higher olefinswere observed.

Example 12

Ethylene Oligomerization Using Ni(tributylBBIM)Cl₂

In an Argon glovebox a toluene slurry was prepared in a 50 ml Parr glassliner by suspending Ni(tributBBIM)Cl₂ (FW 546.22) (8.9 mg, 1.63×10⁻²mmoles) (product of Example 2) in 8.06 g toluene followed by activationwith 2.05 mL of 30% MAO (Al/Ni=650) to obtain a dark suspension. In theglovebox, the glass liner was placed into the Parr reactor. The reactorwas transferred to a hood and then pressurized with 500 psig ofethylene. The solution was stirred (stirring rate 500 RPM) at 25° C. for10 minutes. During the reaction, the pressure dropped to 200 psig. TheParr reactor was repressurized with ethylene to 500 psig and thesolution was stirred at 25° C. for 12 minutes. During this period,pressure dropped again to 200 psig. The repressurization and ethylenereaction were continued seven additional times. The catalyst was stillactive. Finally, the reaction mixture was cooled and unreacted ethylenewas vented to obtain 8.9 g of product. The product was analyzed by gaschromatography-mass spectrometry. GC analysis of the product indicatedpeaks due to butenes and hexenes.

Example 13

Ethylene Oligomerization Using Supported Catalyst

In a round bottom flask Ni(tributBBIM)Cl₂ (FW 546.22) (19.0 mg, 3.5×10⁻²mmoles) (product of Example 2) was dissolved into methylene chloride (16mL) and stirred for 15 minutes. To the purplish solution MAO (30 wt % intoluene) was slowly added to give a greenish colored solution. After 30minutes, silica (Grace-Davidson™ Grade 62 dehydrated) (0.5 gm) was addedand stirring was continued for 18 hours. The flask was heated to 50° C.under vacuum (0.05 mm Hg) for 6 hours to give a dark solid. Thesupported catalyst (1.5472 gm) was placed into a fritted vessel. Thefritted vessel was placed into a 50 ml Parr glass liner, thus suspendingthe supported catalyst. The Parr reactor was sealed then pressurized to500 psig with ethylene. The reaction was run for 24 hours at roomtemperature. The pressure dropped from 500 psi to 300 psi. The reactionmixture was cooled and unreacted ethylene was vented to obtain 1.2 g ofproduct. The product was analyzed by gas chromatography-massspectrometry. GC analysis of the product indicated peaks due to butenes(64%) and hexenes (36%). No peaks corresponding to higher olefins wereobserved.

The foregoing examples clearly demonstrate that the novel composition ofthe instant invention can be used as an effective oligomerizationcatalyst to make α-olefins. More specifically, the examples show howolefinic monomers such as ethylene are readily oligomerized toselectively form short chain α-olefins such as butenes and hexenes.Additionally, the examples show that the catalyst can also be supportedand such supported catalyst may also be used in oligomerizationprocesses. Furthermore, the examples demonstrate that the invention canbe used with or without solvent (i.e., gas phase oligomerization). Theoligomerization can be run in batch, continuous, or reactivedistillation modes. Most importantly, the invention provides a novelorganometallic catalyst and oligomerization method which produces linearα-olefins with a high degree of selectivity and does not producesignificant polymer co-product. These features overcome thedisadvantages of the current organometallic technology discussed abovein the background section. As a final note, experimentation has alsoshown that the invention is truly catalytic as the same catalyst can beused repeatedly to make α-olefins. More specifically, the catalysts usedin the aforementioned examples retain their catalytic activity evenafter numerous runs (i.e., more than about six).

What is claimed is:
 1. A composition comprising: (a) a metal complexhaving the formula LMX(X′)_(n) wherein n equals 0 or 1; X and X′ areindependently selected from the group consisting of halides, hydride,triflate, acetates, borates, C₁ through C₁₂ alkyl, C₁ through C₁₂alkoxy, C₃ through C₁₂ cycloalkyl, C₃ through C₁₂ cycloalkoxy, aryl,thiolates, carbon monoxide, cyanate and olefins; M is selected from thegroup consisting of nickel, palladium and platinum; and L is anitrogen-containing bidentate ligand with more than two nitrogen atoms;and (b) an activating cocatalyst.
 2. The composition according to claim1 wherein L is selected from the group consisting of1,1′-bis(1-methylbenzimidazol-2-yl)-1″-methoxymethane,1,1′-bis(1-butylbenzimidazol-2-yl) pentane, and2,2′-bis(2-(1-ethylbenzimidazol-2-yl))biphenyl.
 3. The compositionaccording to claim 1 wherein X and X′ are independently selected fromthe group consisting of chlorine and bromine.
 4. The compositionaccording to claim 3 wherein said X equals X′.
 5. The compositionaccording to claim 1 wherein L has the formula A(ZR*)_(m)A′ or AA′wherein A and A′ are independently selected from the group consistingof:

wherein R1 is independently selected from the group consisting ofhydrogen, C₁ through C₁₂ alkyl, C₃ through C₁₂ cycloalkyl, aryl, andtrifluoroethyl; R2 and R3 are independently selected from the groupconsisting of hydrogen, C₁ through C₁₂ alkyl, C₃ through C₁₂ cycloalkyl,C₁ through C₁₂ alkoxy, F, Cl, SO₃, C₁ through C₁₂ perfluoroalkyl,trimethylsilyl, and N(CH₃)₂; Z is carbon; R* is independently selectedfrom the group consisting of hydrogen, C₁ through C₁₂ alkyl, C₃ throughC₁₂ cyclo alkyl, aryl, C₁ through C₁₂ alkoxy, F, Cl, SO₃, C₁ through C₁₂perfluoroalkyl, trimethylsilyl, and N(CH₃)₂; m is 1 to
 22. 6. Thecomposition of claim 1 wherein said activating cocatalyst is selectedfrom the group consisting of alkylalumoxanes, aluminum alkyls, aluminumhalides, alkyl aluminum halides, Lewis acids, alkylating agents, andmixtures thereof.
 7. The composition of claim 1 wherein said activatingcocatalyst is methyl alumoxane.
 8. The composition of claim 1 whereinthe ratio of the metal complex to the activating cocatalyst is from1:10⁻² to 1:10⁶.
 9. The composition of claim 1 wherein the compositionis supported.
 10. The composition of claim 9 wherein the composition issupported by silica.
 11. A method for producing α-olefins comprisingcontacting an olefinic monomer or monomers under oligomerizationconditions with a catalyst composition comprising the reaction productof: (a) a metal complex having the formula LMX(X′)_(n) wherein n equals0 or 1; X and X′ are independently selected from the group consisting ofhalides, hydride, triflate, acetates, borates, C₁ through C₁₂ alkyl, C₁through C₁₂ alkoxy, C₃ through C₁₂ cycloalkyl, C₃ through C₁₂cycloalkoxy, aryl, thiolates, carbon monoxide, cyanate and olefins; M isselected from the group consisting of nickel, palladium and platinum;and L is a nitrogen-containing bidentate ligand with more than twonitrogen atoms; and (b) an activating cocatalyst.
 12. The methodaccording to claim 11 wherein L has the formula A(ZR*)_(m)A′ or AA′wherein A and A′ are independently selected from the group consistingof:

wherein R1 is independently selected from the group consisting ofhydrogen, C₁ through C₁₂ alkyl, C₃ through C₁₂ cycloalkyl, aryl, andtrifluoroethyl; R2 and R3 are independently selected from the groupconsisting of hydrogen, C₁ through C₁₂ alkyl, C₃ through C₁₂ cycloalkyl,C₁ through C₁₂ alkoxy, F, Cl, SO₃, C₁ through C₁₂ perfluoroalkyl,trimethylsilyl, and N(CH₃)₂; Z is carbon; R* is independently selectedfrom the group consisting of hydrogen, C₁ through C₁₂ alkyl, C₃ throughC₁₂ cyclo alkyl, aryl, C₁ through C₁₂ alkoxy, F, Cl SO₃, C₁ through C₁₂perfluoroalkyl, trimethylsilyl, and N(CH₃)₂; m is 1 to
 22. 13. Themethod of claim 11 wherein the cocatalyst is selected from the groupconsisting of alkylalumoxanes, aluminum alkyls, aluminum halides, alkylaluminum halides, Lewis acids other than any of the foregoing,alkylating agents and mixtures thereof.
 14. The method of claim 11wherein the cocatalyst is methyl alumoxane.
 15. The method of claim 11wherein the contacting is at a temperature in the range of from about 0to 100° C. and at pressures of from about 15-2000 psig.
 16. The methodof claim 11 wherein the contacting is conducted in a solvent.
 17. Themethod of claim 11 wherein the contacting is conducted neat.
 18. Themethod of claim 11 wherein the contacting is conducted in a gas phase.19. The method of claim 11 wherein said olefinic monomer is selectedfrom the group consisting of ethylene, propylene, butene and mixturesthereof.
 20. The method of claim 11 wherein said olefinic monomer isethylene.